Brake 'spongyness' varies in Eco / normal / sport

[MartinSEsr]

Hi, I've suspected this from experience, then saw a FB post about it...

My golf and other cars I drive have sensitive brakes, linear, but not needing much force or brake travel. When I drive our golf now, I get to traffic lights or an island and everything jerks forwards as the brakes are so 'sharp'.

I've got used to the SE in normal mode, it brakes perfectly fine, they're powerful and stop the car well - BUT the pedal always feels a bit spongy, and seems to have a lot of travel.

I tried sport mode and it was very different, shorter brake pedal travel, less spongy. Much more like a modern car.

Eco seems worse, even more spongy. I never use eco, why would I want to dampen out the accelerator, but I tested it anyway.

In the 'personalised' mode there is a setting for pedal force, but this resets to normal each time, whereas steering force and 'power' stay as selected.

NB does sport mode actually have more 'power' or is it just that the accelerator is more responsive.

Has anyone else noticed the 'spongyness' of the brake pedal in normal or eco mode?

 

[Diggsy]

I don’t have this in mine. Brakes are more than adequate in Normal or Sport mode (never drive it in Eco) and they don’t feel at all ‘spongy’

 

[MartinSEsr]

I don’t have this in mine. Brakes are more than adequate in Normal or Sport mode (never drive it in Eco) and they don’t feel at all ‘spongy’

Thanks, they are adequaite, it's the spongyness... It's being serviced soon, I'll ask them to see what they think. They're picking it up, so it will give a good chance to drive it.

 

[DarrenG]

I noticed this on mine recently. Driving to Devon so selected Eco and didn’t click why the brakes felt so spongy. Noticeably so, very spongy and needing much more force to have an effect. Only when I set off the next day and it defaulted to Normal and brake feel was OK again did the cause dawn on me ?‍

 

[MoDolph]

I've noticed that the brakes are sharper in sport mode as often my first application is too hard after I've switched from normal. I've never used eco so don't know what that is like.

I don't think there is a difference in maximum power between normal and sport but I haven't measured it. I can however only get the back end out in sports mode ?. Sport mode is still not as good accelerator response as my old 24kWh leaf but good enough.

 

[MartinSEsr]

Thanks. By what insane ridiculous logic does eco-mode, and to a lesser extent normal mode, require spongy brakes with more pedal travel?

 

[Rolfe]

One odd thing I have noticed is that if for any reason I use my left foot on the brake, I practically put myself through the windscreen. Which is strange, because my left foot was brought up to be very very delicate at clutch control.

 

[gumboots]

I was wondering if Eco mode might feel different because there could be a bit more regen before the traditional braking gets applied?

 

[Koomi]

Sport does look to give more power (not tested so could be wrong)
If switching between modes, the GOM will drop quite a bit of range when switching into sport... so it must be doing something for the computer to think you will have so many less miles available.

 

[Ian Key]

The accelerator isn't an on and off switch but works on a sliding scale of power delivery a bit like an ICE acceleration curve. The different driving modes sets where the power delivery starts. ECO mode it's at the start of the shallow curve so it is gentle to start with where as in sport mode it starts at the steep end and delivers maximum power with a smaller pedal movement.

I think @gumboots is right about the amount of regen before actual braking is applied depending on the driving mode.

 

[Torryhun]

One odd thing I have noticed is that if for any reason I use my left foot on the brake, I practically put myself through the windscreen. Which is strange, because my left foot was brought up to be very very delicate at clutch control.

OMG, left foot breaking!! You do like living on the edge ?

 

[MartinSEsr]

One odd thing I have noticed is that if for any reason I use my left foot on the brake, I practically put myself through the windscreen. Which is strange, because my left foot was brought up to be very very delicate at clutch control.

Ahh, when I have tried left foot braking in an auto, I've had the same effect. The left foot on a clutch is always harsh going down, but sensitive coming up as it bites, and I think muscle memory always give a hard push on the brakes when braking with the left foot.

 

[fnegroni]

Bear in mind that because of regenerative braking, your discs might not have enough pad material deposited to cause a good initial bite. It’s always a good idea with electric vehicles to once in a while run on minimum regen and do a series of hard braking runs to get them up to temperature and deposit brake pad material on them

 

[bowfer]

Brakes are always a bit iffy in EVs, I’ve yet to come across any that give a completely consistent feel every time.
Allegedly it’s just the shortcomings of using a mixture of motor and hydraulics when you press the brake pedal.
I don’t use one-pedal or high regen settings in any EV so I perhaps notice the inconsistent brake pedal feel more than others.

 

[Gabricolo]

brake by wire system may delay mechanical brake intervention while in eco to ncrease regen or may use more mechanical brakes and less regen whle in sport. during normal drive i noticed that mechanical brakes start to bite at around -20%regen.

 

[2Sheds]

If you are going downhill, regenerating, and then apply the brakes, watch the power reading, you'll see the regen figure increase (negatively that is) - this wouldn't happen if the brakes were operating purely on friction, implying that increased regen is indeed part of the braking process. So it's perhaps not to be unexpected that the feel of the brakes will be different in different driving modes.

 

[tsedge]

I would imagine the philosophy is that ECO mode is all about maintaining momentum and so the accelerator and brake responses should be less sharp.

 

[bowfer]

If you are going downhill, regenerating, and then apply the brakes, watch the power reading, you'll see the regen figure increase (negatively that is) - this wouldn't happen if the brakes were operating purely on friction, implying that increased regen is indeed part of the braking process. So it's perhaps not to be unexpected that the feel of the brakes will be different in different driving modes.

Friction alone can create regeneration though.
Petrol and diesel cars can have regenerative braking system that help recharge the battery.
They don’t have any electric motor involved, so the friction alone is creating it.

 

[Rolfe]

Ahh, when I have tried left foot braking in an auto, I've had the same effect. The left foot on a clutch is always harsh going down, but sensitive coming up as it bites, and I think muscle memory always give a hard push on the brakes when braking with the left foot.

That could well be it. I've not tried both-feet driving, it's just that once or twice when doing some sort of manoeuvre (at a very slow speed, like moving the car or parking) it seemed more convenient to use my left foot, and bang, very sudden stop.

OMG, left foot breaking!! You do like living on the edge ?

Braking! You'll have @siteguru after you!

 

[2Sheds]

Friction alone can create regeneration though.
Petrol and diesel cars can have regenerative braking system that help recharge the battery.
They don’t have any electric motor involved, so the friction alone is creating it.

Hmmm. If they are recharging the battery, then an electrical generator of some kind is involved somewhere! I did a bit of googling on this. I can only find systems that generate via an alternator which kicks in when the throttle is lifted, and which charges the 12v battery or a capacitor, which is then used to power the vehicles ancillaries (AC, audio, lights, etc). The purpose of these systems is not to produce an additional braking effect (although it will, albeit a small one, via the extra load placed on the engine by the alternator) but rather to improve overall efficiency and hence economy. So effectively, this is using the same principles as the EV regen, friction not involved per se.

Incidentally, whilst reading these articles on regenerative braking, it's remarkable how many of them state that it is achieved by "reversing the motor". It isn't of course, what reverses is the direction of current through the motor when the wheels drive it (making it a generator) rather than when it is driving the wheels (motoring).